[The behaviour of the granular alveocytes in chronic pulmonary congestion, pulmonary fibrosis and after extracorporeal circulation (author's transl)].

The granular alveocytes, known to be the site of the production of the surfactant, undergo characteristic changes following chronic pulmonary congestion and the succeeding fibrosis, and after extracorporeal circulation. Congestion is accompanied by cell edema and the breakdown of the lamellar bodies. With fibrosis the cells are shrunken and present with little if any lysosomes. The nuclei are pyknotic or demonstrate karyolysis. Vacuolar degeneration of the lamellar bodies and progressive degeneration of the mitochondria are observed. The extracorporeal circulation damages many granular alveocytes. The degree of damage correlates with the duration of the cardiopulmonary bypass and with the degree of the prepump pathological changes present in the lungs. On the other and the extracorporeal circulation induces in the intact cells enhanced surfactant production, during which the different developmental stages of the lamellar body increasingly accumulate within the cell. In conclusion, pulmonary congestion and fibrosis reduce the activity of the granular alveocytes. The extracorporeal circulation enhances structurally favourable conditions in the granular alveocytes for the increased release of the surfactant in the immediate post-operative phase - a process which could be regarded as an autoregulatory mechanism.